The last tale told of how the Thunderbird, after laying waste to Tsurumi Island, flew onward to Seirai Island.
According to both the records in The Chronicles of the Distant Seas and the deductions of Sango, the head of the Bantan Sango Detective Agency, it was on Seirai Island—at a place called Amakumo Peak—that the Thunderbird was ultimately destroyed by the Raiden Shogun.
Though the Thunderbird bore no divine title, it was a being of immense power. Even in death, its strength did not fade. Losing control, its residual energy rampaged wildly, posing an even greater threat to mortals than when it lived. To contain this power, the people of Seirai Island erected the Asase Shrine. Yet, many years later, that sealed force erupted once again.
As another island devastated by the Thunderbird's wrath, Seirai Island too harbored a tragic story—one that was both sorrowful and difficult to judge.
And this story begins with a shrine maiden named Asase Hibiki.
Bearing the Asase family name, Hibiki was bound by duty to maintain Seirai Island's barrier and preserve the Asase Shrine. In her youth, she traveled to the Grand Narukami Shrine to study under Fox Priestess Saiguu, learning how to manage shrine affairs. During that time, she met a man who would change her life forever.
History never recorded this man's full name. Most only knew him by his surname, Takamine, and his nickname—Konbumaru.
In his youth, Konbumaru made a reckless wager with Reizenbou, a mighty tengu of Mount Yougou (not Sasayuri). They fought to a draw—an outcome so rare that Reizenbou took him as his servant, while Konbumaru earned a prize: the unparalleled bow Thundering Pulse, bestowed upon Reizenbou by the Raiden Shogun herself.
Under the tengu's tutelage, Konbumaru honed both archery and swordsmanship. As he grew older, Reizenbou recommended him to the shogunate, where he was personally granted the legendary blade Mistsplitter Reforged by the Raiden Shogun.
Konbumaru became renowned for his mastery of both the bow and the sword. Children sang songs of famed warriors, naming him alongside Arataki of the Front Gate, Iwakura the Successor, and Kitain the Serpent, together known as Takamine the Mistsplitter.
Since Mount Yougou and the Grand Narukami Shrine were close neighbors, and Fox Priestess Saiguu was acquainted with Reizenbou, Asase Hibiki and Konbumaru came to know each other. Affection bloomed between them, though neither dared confess. Eventually, Konbumaru became a hatamoto—a direct retainer of the Shogun, charged with guarding Tenshukaku—and married the daughter of a high-ranking samurai. To this day, no one knows whether that was by choice or duty. Regardless, his relationship with Hibiki remained unchanged.
Then came the inevitable calamity that every tale of Inazuma must face—the Dark Calamity.
As Konbumaru prepared for battle, he entrusted the Thundering Pulse to Asase Hibiki. He made a wager with her, much like the one he once made with the tengu: a gamble on whether he would return alive. The stakes were the same—the only difference was the roles had reversed. If he lost, the bow would belong to Hibiki. If he won…
But no blade, no matter how divine, could outlast the will of its wielder. The skies turned black as the battle raged without end. Even the Mistsplitter Reforged, the blade personally granted by the Shogun, shattered under his relentless strikes. The famed Takamine of the Mistsplitter was swallowed by the pitch-black mists of the calamity.
Decades—perhaps centuries—passed. Then, miraculously, Konbumaru returned from the Abyss. At the promised place, he met Asase Hibiki again—no longer young, yet still waiting. For a fleeting moment, the lifeless blackness in his eyes flickered with light.
But even the mighty Torachiyo could not resist the corruption of the darkness. Even the Raiden Shogun herself could not cleanse the black taint from his soul. How long could that faint glimmer in Konbumaru's eyes truly last?
Asase Hibiki, clutching the bow he left behind, drew upon the archery he had taught her—and shot him through the heart.
Years later, Hibiki met another man—Ako Domeki a pirate who prowled the seas near Seirai Island. He resembled Konbumaru so much that Hibiki regarded him as her own son. But the shogunate army was coming to purge the pirates.
Perhaps Hibiki still carried resentment—resentment that the Raiden Shogun had failed to protect Inazuma. Because of that failure, Fox Priestess Saiguu, her mentor and friend, had died; the mighty tengu who had once been a kind elder to her had exiled himself and vanished; her dear companion Kamuna Harunosuke had left Inazuma in sorrow. And Konbumaru… If Konbumaru had lived, their child would be about the same age as Ako Domeki now.
She made a choice: this time, she would not let him die—no matter the cost, even if it meant defying the Shogun herself.
In doing so, she committed a grave sin. The barrier over Seirai Island was broken. The Thunderbird's sealed power rampaged once more, laying waste to everything.
That—was the true story of Seirai Island.
Victor Wang wanted to tell it all—but had to keep it to himself.
After Lumine resolved the crisis at Mikage Furnace in Tatarasuna, and following a brief rest of two days, the Inazuma branch of the Adventurers' Guild finally began recruiting explorers to investigate Seirai Island.
Until then, the guild had only stationed two resident adventurers on the island to research the thunderstorm's cause. But after a long period without progress, rumors began to spread—rumors of hidden treasures buried across Seirai Island. Treasure hunters and the Treasure Hoarders alike grew restless.
Some rumors even got oddly specific—claiming that a five-star weapon lay hidden there: none other than Asase Hibiki's Thundering Pulse.
Back then, the fragments of Mistsplitter Reforged had been left scattered across the battlefield of the Dark Calamity. When the darkness subsided, the fragments were gathered and reforged into the Mistsplitter Reforged Blade, which is now held by the Kamisato Clan of the Yashiro Commission, descendants of the smithing family that once forged such blades.
As for the Thundering Pulse, it truly had vanished five hundred years ago. The last person known to wield it—Asase Hibiki—had disappeared on Seirai Island. And yet, all these rumors were vague and fragmented.
Some couldn't even recall Konbumaru or Hibiki's names—getting the outcome right, but the story all wrong.
As Katheryne briefed Victor Wang and Lumine, she said, "It's said that Seirai Island hides many treasures. If you're interested, you can head there and take a look. But please be careful during your exploration—the guild still doesn't understand the cause of those thunderstorms."
Having blocked three of the Raiden Shogun's strikes head-on, Victor Wang had earned the title of Grand Adventurer, a rank equal to that of a senior adventurer. Because of that, whenever nearby branches organized important missions, he would be among the first notified—proof of the guild's trust in his strength.
"Treasure!" As always, Paimon was instantly drawn in by the word.
"Even if there's no treasure," Lumine added, "we'd still have to visit Seirai Island anyway—there are so many we still haven't collected…"
So many Electroculi remained unfound—it was exhausting. Thankfully, ever since the start, they'd been using the precise map markers provided by Victor, saving them a great deal of effort. Still, curiosity gnawed at Lumine, and after hesitating for a while, she finally asked.
Victor Wang shrugged. "That's all Little Wen's doing. She claims she's been crawling and exploring for over a hundred thousand years. If that's true, knowing every inch of Teyvat isn't too surprising."
["Hmph! Of course it's true! What possible benefit would I get from lying about that?"]
Paimon blinked in disbelief. "Wait—someone can actually live for a hundred thousand years?"
["I'm not human! You annoying unidentified flying object—are you mocking me on purpose?!"]
"I'm not! I didn't mean to! I just—kind of forgot you're… a rock."
["Unidentified flying object!"]
"Brain-dead rock!"
Lumine smiled helplessly at the two quarreling companions and pushed her doubts aside. Then she asked Victor Wang, "Are you coming with us to Seirai Island? Now that I think about it, we've known each other this long, but we've never actually gone on a mission together."
"That's exactly my plan. In fact, I already know what's causing the thunderstorms on Seirai Island."
"You know?"
"It was the Raiden Shogun who told me. Seirai Island was once used to seal away a powerful Electro creature. When the barrier broke, the thunderstorms began. My goal is to defeat that creature and obtain its drops. Since it can fly, I plan to call in one more helper."
"Something that agile will be hard to fight, huh?"
…
"So, your helper is Yoimiya, huh? Perfect timing—there are also rumors about a lost five-star bow on Seirai Island. We can look for it while collecting the Electroculi and treasure!"
"No need, no need! My current bow works just fine. Besides, I don't fight all that often—you don't need to go out of your way for me."
"Not much fighting? You sure about that? You made quite a scene last time we went to the Tenryou Commission to rescue Master Masakatsu!"
"Eh-heh… That was just because I'm, you know, spirited! But since this is to help a friend, I'll definitely give it my all in battle!"
"Oh-oh! So reliable, Yoimiya!"
After meeting with the two adventurers stationed on Seirai Island, they pretended not to know how to use the warding stones. Following cat pawprints near the site, they reached the Asase Shrine. After a bit of petting cats—ahem, conversing—with the talking cat Neko, the acting shrine head, they helped repair the offering box and learned how to control the warding stones.
Under Victor Wang's subtle guidance, everything proceeded smoothly.
The island's thunderstorms began to shrink. The Thunderbird's scattered power was gradually sealed again. The stones floating over Amakumo Peak—disrupted by abnormal energy—were caught in a net of lightning chains when the last storm was suppressed. Amid the roar of thunder and rock, they fused into a massive platform.
From that platform, the grudge of the dead Thunderbird—its unspent fury—took form once more. The Thunder Manifestation had appeared.
"This thing really can fly—ugh, it won't stay still for even a second!"
"Heh-heh! My turn to shine!"
Yoimiya nimbly pulled out a bundle of custom fireworks from her pouch. Flames of Pyro swirled around her as she gripped a magnificent violet bow in her left hand, drawing the string with her right. Fiery arrows soared, bursting brilliantly against the storming sky as they struck the Thunder Manifestation.
Victor Wang's gaze flicked toward her weapon again and again—he couldn't believe what he was seeing.
That bow in her hands… wasn't it the Thundering Pulse?